A wide range of organic amendments (OA) is currently available to Australian farmers. These products have numerous agronomic applications, including the supply of plant nutrients, control of pests and diseases, and in management of soil health. Several of these products are also used in contaminated and degraded land remediation. The most commonly identifiable groups of OA in Australia are composts, compost teas, vermicasts, humic substances, meat, blood and bone meal, fish hydrolysates, seaweed extracts, bio-inoculants, biodynamic products, and biochars. Many of these OA contain nutrients within organic molecular structures; these nutrients are usually not immediately available to plants and must first be mineralised. Mineralisation often occurs as OA are consumed by microbes, thereby stimulating soil microbial activity. The application of OA such as bio-inoculants, humic substances, and seaweed extracts can potentially stimulate crop growth and development through the actions of plant growth-promoting hormones, including cytokinins, auxins, and gibberellins. Yet despite these apparent benefits, the widespread adoption of OA in Australia has been limited, due in part to the high application rates required to produce agronomic benefits, a lack of consistency in the composition of some products, a poor public perception of their utility, and a lack of unbiased scientific research into the agricultural potential of these products.

https://www.soilwealth.com.au/imagesDB/news/amendmentreview2011.pdf

Use and understanding of organic amendments in Australian agriculture: a review

The biofertilization of crops with plant-growth-promoting microorganisms is currently considered as a healthy alternative to chemical fertilization. However, only microorganisms safe for humans can be used as biofertilizers, particularly in vegetables that are raw consumed, in order to avoid sanitary problems derived from the presence of pathogenic bacteria in the final products. In the present work we showed that Rhizobium strains colonize the roots of tomato and pepper plants promoting their growth in different production stages increasing yield and quality of seedlings and fruits. Our results confirmed those obtained in cereals and alimentary oil producing plants extending the number of non-legumes susceptible to be biofertilized with rhizobia to those whose fruits are raw consumed. This is a relevant conclusion since safety of rhizobia for human health has been demonstrated after several decades of legume inoculation ensuring that they are optimal bacteria for biofertilization.

/pdf/rhizobium-promotes-non-legumes-growth-and-quality-in-several-1fyyuracr2.pdf

Rhizobium promotes non-legumes growth and quality in several production steps: towards a biofertilization of edible raw vegetables healthy for humans.

Agricultural waste recycling in horticultural intensive farming systems by on-farm composting and compost-based tea application improves soil quality and plant health: A review under the perspective of a circular economy.

Numerous studies have demonstrated the potential of composted organic wastes not only as substitutes for peat as a growth substrate but also to stimulate plant growth and suppress soil-borne diseases. The major impediment to the use of compost as substrates or biocontrol agents has been variation in physical and chemical characteristics and disease suppression levels across and within compost types, sources, and batches. Compost tea, a product of compost, has also been shown to suppress soil-borne diseases including damping-off and root rots (Pythium ultimum, Rhizoctonia solani, Phytophthora spp.) and wilts (Fusarium oxysporum and Verticillium dahliae). Although the mechanisms involved in disease suppression are not fully understood, sterilization of composts and compost teas has generally resulted in a loss in disease suppressiveness. This indicates that the mechanism of suppression is often, or predominantly, biological, although chemical and physical factors have also been implicated. The inoculation o...

Souleymane B. Koné

Papers

Suppressive effect of non-aerated compost teas on foliar fungal pathogens of tomato